The invention provides novel methyl substituted norbornane carboxaldehydes having the generic structure: ##STR2## wherein the dashed line is a carbon-carbon single bond or a carbon-carbon double bond, and R.sub.1, R.sub.2 and R.sub.3 represent methyl or hydrogen with the proviso that (i) R.sub.1 is hydrogen when R.sub.3 is methyl and (ii) R.sub.1 is methyl when R.sub.3 is hydrogen and uses thereof for their organoleptic properties in the consumable materials.
Materials which can provide green, cut grass-like and minty aromas with fruity (apple) and herbaceous undertones are known in the art of perfumery. Many of the natural substances which provide such fragrances and contribute the desired nuances to perfumery compositions are high in cost, vary in quality from one batch to another and/or are generally subject to the usual variations of natural products.
By the same token, materials which can provide eucalyptus-like, camphoraceous , blueberry-like, patchouli-like and fruity aroma nuances and camphoraceous, blueberry-like, patchouli-like flavor nuances are well known in the art of flavoring for foodstuffs, toothpastes, chewing gums and medicinal products. Many of the natural materials which provide such flavor notes and contribute desired nuances to flavor and to compositions are high in cost, vary in quality from one batch to another and/or are generally subject to the usual variations of natural products.
There is accordingly, a continuing effort to find synthetic materials which will replace, enhance or augment the essential flavor and fragrance notes provided by natural essential oils or compositions thereof. Unfortunately, many of these synthetic materials have the desired nuances only to a relatively small degree or else contribute undesirable or unwanted odor to the compositions. The search for materials which can provide a more refined blueberry flavor or raspberry flavor, for example, has been difficult and relatively costly in the areas of both natural products and synthetic products.
Artificial flavoring agents for foodstuffs have received increasing attention in recent years. For many years such food flavoring agents have been preferred over natural flavoring agents at least in part due to their diminished cost and their reproducible flavor qualities. For example, natural flavoring agents such as, extracts, concentrates and the like are often subject to wide variations due to changes in quality, type and treatment of the raw materials. Such variations can be reflected in the end product and result in unfavorable flavor characteristics in said end product. Additionally, the presence of the natural product in the ultimate food may be undesirable because of increased tendency to spoil. This is particularly troublesome in food and food uses where such products as dips, ice cream desserts and yogurt desserts and the like are apt to be stored prior to use.
The fundamental problem in creating artifical flavor agents is that the artificial flavor to be achieved be as natural as possible. This generally proves to be a difficult task since the negativism for flavor development in many foods, medicinal products, chewing gums and toothpastes is not completely known. This is noticeable in products having raspberry and blueberry flavor characteristics, particularly.
Even more desirable are products that can serve to substitute for difficult-to-obtain natural perfumery oils and at the same time substitute for natural flavoring agents in foodstuffs, chewing gums, medicinal products and toothpastes.
The prior art contains a large number of teachings wherein compounds having the aldehyde moiety or compounds having the norbornane moiety are useful in augmenting or enhancing the organoleptic properties of consumable materials. However, nothing in the prior art discloses the use for its organoleptic properties of any of the compounds defined according to the generic structure: ##STR3## wherein R.sub.1, R.sub.2 and R.sub.3 represent hydrogen or methyl and wherein the dashed line represents a single or double bond with the proviso that when R.sub.1 is hydrogen, R.sub.3 is methyl, and that when R.sub.1 is methyl, R.sub.3 is hydrogen. The prior art does show a compound having a similar but patentably distinct structure as an intermediate for producing compounds having organoleptic properties useful in augmenting or enhancing the aroma or taste of consumable materials. Thus, U.S. Pat. No. 4,143,074 in Example I discloses the use as an intermediate in preparing alcohols and ketones, the compound having the structure: ##STR4##
This compound is different in kind, in structure and in properties from the compounds defined according to the generic structure: ##STR5## wherein the dashed line represents a carbon-carbon single bond or a carbon-carbon double bond and R.sub.1, R.sub.2 and R.sub.3 represent hydrogen or methyl with a proviso that R.sub.1 is hydrogen when R.sub.3 is methyl and R.sub.1 is methyl when R.sub.3 is hydrogen.
U.S. Pat. No. 3,067,244 issued on Dec. 4, 1962 discloses interalia Diels-Alder reaction products of conjugated dienes including cyclopentadiene (at Column 1 line 64 with alpha, beta unsaturated alkanols at (Column 2 line 15) having the structure: ##STR6## wherein R.sup.1 represents one of hydrogen, hydroxyl or alkyl and R.sup.2 represents hydrogen, carboxcyclic acid or alkyl. Included in the large list of unsaturated alkanols is acrolein at Column 2 line 42. Disclosed also in U.S. Pat. No. 3,067,244 is the process involving reaction of the conjugated diene and dienophile using Lewis acids including aluminum diethylchloride and aluminum ethyl dichloride but also including other Lewis acids, titanium tetrachloride, stannic chloride, aluminum trichloride, ferric chloride, zinc chloride and boron trifluoride. The reaction involving methyl cyclopentadienes and unsaturated dienophiles such as acrolein and crotonaldehyde, however, is not disclosed in U.S. Pat. No. 3,067,244 nor are the unobvious, unexpected and advantageous organoleptic properties of the resultant product suggested in U.S. Pat. No. 3,067,244. Indeed, there is no suggestion that in the reaction of the methylcyclopentadienes and the unsaturated alkanols of our invention only ethyl aluminum dichloride and aluminum diethyl chloride and their corresponding bromides will be usable as catalysts for the reaction, the other "catalysts" listed at lines 51-55 of Column 2 of U.S. Pat. No. 3,067,244 not being workable for the reaction of our invention. Indeed, in a paper published at Page 249 of the Jan. 5, 1961 issue of the Journal of the American Chemical Society entitled "Catalysts of the Diels-Alder Reaction" by Fray & Robinson, the inventors on U.S. Pat. No. 3,067,244, it was further mentioned that "In comparative experiments with methylvinylketone and titamium tetrachloride . . . cyclopentadiene yielded only polymer and dimer respectively . . . "